Detector structure in a pet system

ABSTRACT

The present disclosure relates to a PET detector and a PET frame. The PET detector may include a plurality of detector modules and a plurality of installing modules configured to install the plurality of detector modules. The plurality of installing modules may be coupled together to form a detector ring. The PET frame may include a detector stabilizing cylinder configured to stabilize a detector and a fixing support configured to support the detector stabilizing cylinder. The detector stabilizing cylinder may be rotatably fixed on the fixing support.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority of Chinese Patent Application No.201710072902.X filed on Feb. 10, 2017, and Chinese Patent ApplicationNo. 201610899083.1 filed on Oct. 14, 2016, the entire contents of eachof which are hereby incorporated by reference.

TECHNICAL FIELD

The present disclosure generally relates to a positron emissiontomography (PET) system, and more particularly, relates to a detectorstructure of the PET system.

BACKGROUND

Positron emission tomography (PET) is a technology that is used toobserve metabolic processes in the body. The PET technology has beenwidely used in medical diagnosis. The PET technology may use a pluralityof detector modules that form a detector ring to detect pairs of gammarays emitted indirectly by a positron-emitting radionuclide, which isintroduced into the body on a biologically active molecule. It isdesirable to provide a detector structure with simplicity ofinstallation and maintenance.

SUMMARY

In a first aspect of the present disclosure, a PET detector is provided.The PET detector may include a plurality of detector modules and aplurality of installing modules configured to install the plurality ofdetector modules. In some embodiments, the plurality of installingmodules may be coupled together to form a detector ring.

In some embodiments, at least one of the plurality of installing modulesmay include a chain piece, and the chain piece may further include aninstalling groove on a surface connected to one of the plurality ofdetector modules. In some embodiments, the one of plurality of detectormodules may further include a sliding part corresponding to theinstalling groove. In some embodiments, the sliding part may beinstalled in the installing groove.

In some embodiments, the plurality of installing modules may include afirst chain piece and a second chain piece. In some embodiments, thefirst chain piece and the second chain piece may be adjacent. In someembodiments, each of the first chain piece and the second chain piecemay include a convex part at one end along a circumferential directionof the detector ring and a recessed part at the other end along thecircumferential direction of the detector ring. In some embodiments, theconvex part of the first chain piece may be coupled to the recessed partof the second chain piece via a rotation axis.

In some embodiments, the second chain piece may further include aposition-limiting surface on one end of the second chain piece adjacentto the first chain piece. In some embodiments, the position-limitingsurface may be configured to determine an angle formed by the firstchain piece and the second chain piece.

In some embodiments, the plurality of installing modules may include afirst chain piece and a second chain piece. In some embodiments, thefirst chain piece and the second chain piece may be adjacent. In someembodiments, each of the first chain piece and the second chain piecemay include two hinge parts on both ends along a circumferentialdirection of the detector ring and a rotation axis corresponding to eachof the two hinge parts. In some embodiments, the first chain piece andthe second chain piece may be coupled together by the respective hingeparts and the rotation axis.

In some embodiments, the rotation axis may be located at a position ofthe hinge part close to the center of the detector ring.

In some embodiments, the PET detector may further include a connectionpart configured to connect the first chain piece and the second chainpiece.

In some embodiments, each of the first chain piece and the second chainpiece may further include a stabilizing plate, and the connection partmay be configured to connect the stabilizing plates of the first chainpiece and the second chain piece.

In some embodiments, the PET detector may include at least two detectorrings formed by the plurality of detector modules and the plurality ofinstalling modules. In some embodiments, the at least two detector ringsmay be arranged parallel to an axial direction of the at least twodetector rings.

In a second aspect of the present disclosure, another PET detector isprovided. The PET detector may include a plurality of detector modulesand a plurality of installing modules configured to install theplurality of detector modules. In some embodiments, the plurality ofinstalling modules may be sequentially connected to form a detachablering structure. In some embodiments, the detachable ring structure mayinclude an outer circumference surface and an inner circumferencesurface spaced apart along a radial direction of the detachable ringstructure. In some embodiments, the plurality of detector modules may becontinuously arranged along the inner circumference surface of thedetachable ring structure.

In a third aspect of the present disclosure, a PET frame is provided.The PET frame may include a detector stabilizing cylinder configured tostabilize one or more detector modules and a fixing support configuredto support the detector stabilizing cylinder. In some embodiments, thedetector stabilizing cylinder may be rotatably fixed on the fixingsupport.

In some embodiments, the fixing support may be configured to fix thedetector stabilizing cylinder through a rolling wheel.

In some embodiments, the fixing support may include a front fixingsupport and a rear fixing support. In some embodiments, the rollingwheel may be fixed between the front fixing support and the rear fixingsupport by a scrollable axis.

In some embodiments, the rolling wheel may include at least two rollingwheels. The two rolling wheels may be located on both sides of avertical center line of the detector stabilizing cylinder, respectively,and be beneath a horizontal center line of the detector stabilizingcylinder.

In some embodiments, the rolling wheel may include at least one drivewheel configured to drive the detector stabilizing cylinder to rotate onthe fixing support.

In some embodiments, the rolling wheel may include an axialposition-limiting wheel configured to limit an axial position of thedetector stabilizing cylinder and a radial position-limiting wheelconfigured to limit a radial position of the detector stabilizingcylinder.

In some embodiments, the rolling wheel may include at least one axialposition-limiting wheel and at least two radial position-limitingwheels.

In some embodiments, the at least one axial rolling wheel and the atleast two radial position-limiting wheels may be uniformly distributedalong a circumferential direction of the detector stabilizing cylinder.

In some embodiments, the rolling wheel may include four axialposition-limiting wheels and four radial position-limiting wheels.

In some embodiments, the PET frame may further include a brake partconfigured to immobilize the detector stabilizing cylinder.

Additional features will be set forth in part in the description whichfollows, and in part will become apparent to those skilled in the artupon examination of the following and the accompanying drawings or maybe learned by production or operation of the examples. The features ofthe present disclosure may be realized and attained by practice or useof various aspects of the methodologies, instrumentalities andcombinations set forth in the detailed examples discussed below.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure is further described in terms of exemplaryembodiments. These exemplary embodiments are described in detail withreference to the drawings. These embodiments are non-limiting exemplaryembodiments, in which like reference numerals represent similarstructures throughout the several views of the drawings, and wherein:

FIG. 1 is a block diagram illustrating an exemplary imaging systemaccording to some embodiments of the present disclosure;

FIG. 2 is a block diagram illustrating an exemplary PET scanneraccording to some embodiments of the present disclosure;

FIG. 3 is a block diagram illustrating an exemplary PET scanneraccording to some embodiments of the present disclosure;

FIG. 4 is a schematic diagram illustrating an exemplary PET detectormodule according to some embodiments of the present disclosure;

FIG. 5 illustrates an exemplary PET detector assembly according to someembodiments of the present disclosure;

FIG. 6 illustrates an exemplary connection manner of a plurality of PETdetector assemblies according to some embodiments of the presentdisclosure;

FIG. 7 illustrates an exemplary detector ring according to someembodiments of the present disclosure;

FIG. 8 illustrates an exemplary PET detector assembly according to someembodiments of the present disclosure;

FIG. 9 illustrates an exemplary connection manner of two PET detectorassemblies according to some embodiments of the present disclosure;

FIG. 10 illustrates an exemplary detector ring according to someembodiments of the present disclosure;

FIG. 11 illustrates an exemplary PET detector assembly according to someembodiments of the present disclosure;

FIG. 12 illustrates an exemplary detector ring according to someembodiments of the present disclosure;

FIG. 13 illustrates an exemplary detector ring according to someembodiments of the present disclosure;

FIG. 14 illustrates an exemplary PET detector according to someembodiments of the present disclosure;

FIG. 15 illustrates an exemplary detector stabilizing cylinder accordingto some embodiments of the present disclosure;

FIG. 16 illustrates the front view of an exemplary detector stabilizingcylinder according to some embodiments of the present disclosure;

FIG. 17 illustrates an exemplary PET detector according to someembodiments of the present disclosure;

FIG. 18 illustrates the front view of an exemplary PET detectoraccording to some embodiments of the present disclosure;

FIG. 19 illustrates the side view of an exemplary PET detector accordingto some embodiments of the present disclosure; and

FIG. 20 illustrates an exemplary PET detector according to someembodiments of the present disclosure.

DETAILED DESCRIPTION

The following description is presented to enable any person skilled inthe art to make and use the present disclosure, and is provided in thecontext of a particular application and its requirements. Variousmodifications to the disclosed embodiments will be readily apparent tothose skilled in the art, and the general principles defined herein maybe applied to other embodiments and applications without departing fromthe spirit and scope of the present disclosure. Thus, the presentdisclosure is not limited to the embodiments shown, but is to beaccorded the widest scope consistent with the claims.

The terminology used herein is for the purpose of describing particularexemplary embodiments only and is not intended to be limiting. As usedherein, the singular forms “a,” “an,” and “the” may be intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprise,”“comprises,” and/or “comprising,” “include,” “includes,” and/or“including,” when used in this specification, specify the presence ofstated features, integers, steps, operations, elements, and/orcomponents, but do not preclude the presence or addition of one or moreother features, integers, steps, operations, elements, components,and/or groups thereof.

It will be understood that the term “system,” “engine,” “unit,” and/or“module” used herein are one method to distinguish different components,elements, parts, section or assembly of different level in ascendingorder. However, the terms may be displaced by other expression if theyachieve the same purpose.

It will be understood that when a unit, engine or module is referred toas being “on,” “connected to,” or “coupled to,” another unit, engine, ormodule, it may be directly on, connected or coupled to, or communicatewith the other unit, engine, or module, or an intervening unit, engine,or module may be present, unless the context clearly indicatesotherwise. As used herein, the term “and/or” includes any and allcombinations of one or more of the associated listed items.

These and other features, and characteristics of the present disclosure,as well as the methods of operation and functions of the relatedelements of structure and the combination of parts and economies ofmanufacture, may become more apparent upon consideration of thefollowing description with reference to the accompanying drawings, allof which form a part of the present disclosure. It is to be expresslyunderstood, however, that the drawings are for the purpose ofillustration and description only and are not intended to limit thescope of the present disclosure. It is understood that the drawings arenot to scale.

FIG. 1 is a block diagram illustrating an exemplary imaging system 100according to some embodiments of the present disclosure. The imagingsystem 100 may be a single modality imaging system including, forexample, a digital subtraction angiography (DSA) system, a magneticresonance imaging (MRI) system, a computed tomography angiography (CTA)system, a positron emission tomography (PET) system, a single photonemission computed tomography (SPECT) system, a computed tomography (CT)system, a digital radiography (DR) system, etc. In some embodiments, theimaging system 100 may be a multi-modality imaging system including, forexample, a positron emission tomography-computed tomography (PET-CT)system, a positron emission tomography-magnetic resonance imaging(PET-MRI) system, a single photon emission computed tomography-positronemission tomography (SPECT-PET) system, a digital subtractionangiography-magnetic resonance imaging (DSA-MRI) system, etc. For betterunderstanding the present disclosure, a PET system may be described asan example of the imaging system 100. It should be noted that theimaging system 100 described below is merely provided for illustrationpurposes, and not intended to limit the scope of the present disclosure.

As shown in FIG. 1, the imaging system 100 may include a PET scanner110, an examining table 120, a processing engine 130, a network 140, astorage device 150, and one or more terminal devices 160. In someembodiments, the PET scanner 110, the examining table 120, theprocessing engine 130, the storage device 150, and/or the terminaldevice 160 may be connected to and/or communicate with each other via awireless connection (e.g., the network 140), a wired connection, or anycombination thereof.

The PET scanner 110 may generate a medical image or provide image databased on PET signals via scanning a subject, or part of the subject. Insome embodiments, the PET scanner 110 may include a detector that maycapture the PET signals relating to the subject. In some embodiments,the PET signals may be electrical signals. The electrical signals maycorrespond to an event when a photon is detected by a photovoltaicdevice. The PET scanner 110 will be discussed in detail in connectionwith FIG. 2.

In some embodiments, the subject may include a body, a substance, anobject, or the like, or any combination thereof. In some embodiments,the subject may be a specific portion of a body, a specific organ, or aspecific tissue, such as head, brain, neck, body, shoulder, arm, thorax,cardiac, stomach, blood vessel, soft tissue, knee, feet, or the like, orany combination thereof. In some embodiments, the PET scanner 110 maytransmit the image data via the network 140 to the processing engine130, the storage device 150, and/or the terminal device 160. Forexample, the image data may be sent to the processing engine 130 forfurther processing, or may be stored in the storage device 150.

The processing engine 130 may process data and/or information obtainedfrom the PET scanner 110, the storage device 150, and/or the terminaldevice 160. For example, the processing engine 130 may process the imagedata and determine a PET image based on the image data. As anotherexample, the processing engine 130 may determine one or more imagingparameters (e.g., imaging radiation dose) based on a scanning protocol.In some embodiments, the processing engine 130 may be a single server ora server group. The server group may be centralized or distributed. Insome embodiments, the processing engine 130 may be local or remote. Forexample, the processing engine 130 may access information and/or datafrom the PET scanner 110, the storage device 150, and/or the terminaldevice 160 via the network 140. As another example, the processingengine 130 may be directly connected to the PET scanner 110, theterminal device 160, and/or the storage device 150 to access informationand/or data. In some embodiments, the processing engine 130 may beimplemented on a cloud platform. For example, the cloud platform mayinclude a private cloud, a public cloud, a hybrid cloud, a communitycloud, a distributed cloud, an inter-cloud, a multi-cloud, or the like,or any combination thereof.

The network 140 may include any suitable network that can facilitateexchange of information and/or data for the imaging system 100. In someembodiments, one or more components of the imaging system 100 (e.g., thePET scanner 110, the examining table 120, the processing engine 130, thestorage device 150, or the terminal device 160) may communicateinformation and/or data with one or more other components of the imagingsystem 100 via the network 140. For example, the processing engine 130may obtain image data from the PET scanner 110 via the network 140. Asanother example, the processing engine 130 may obtain user instructionsfrom the terminal device 160 via the network 140. The network 140 mayinclude a public network (e.g., the Internet), a private network (e.g.,a local area network (LAN), a wide area network (WAN)), etc.), a wirednetwork (e.g., an Ethernet network), a wireless network (e.g., an 802.11network, or a Wi-Fi network), a cellular network (e.g., a Long TermEvolution (LTE) network), a frame relay network, a virtual privatenetwork (“VPN”), a satellite network, a telephone network, routers,hubs, switches, server computers, or the like, or any combinationthereof. For example, the network 140 may include a cable network, awireline network, a fiber-optic network, a telecommunications network,an intranet, a wireless local area network (WLAN), a metropolitan areanetwork (MAN), a public telephone switched network (PSTN), a Bluetooth™network, a ZigBee™ network, a near field communication (NFC) network, orthe like, or any combination thereof. In some embodiments, the network140 may include one or more network access points. For example, thenetwork 140 may include wired and/or wireless network access points suchas base stations and/or internet exchange points through which one ormore components of the imaging system 100 may be connected to thenetwork 140 to exchange data and/or information.

The storage device 150 may store data, instructions, and/or any otherinformation. In some embodiments, the storage device 150 may store dataobtained from the processing engine 130 and/or the terminal device 160.In some embodiments, the storage device 150 may store data and/orinstructions that the processing engine 130 may execute or use toperform exemplary methods described in the present disclosure. In someembodiments, the storage device 150 may include a mass storage, aremovable storage, a volatile read-and-write memory, a read-only memory(ROM), or the like, or any combination thereof. Exemplary mass storagemay include a magnetic disk, an optical disk, a solid-state drive, etc.Exemplary removable storage may include a flash drive, a floppy disk, anoptical disk, a memory card, a zip disk, a magnetic tape, etc. Exemplaryvolatile read-and-write memory may include a random access memory (RAM).Exemplary RAM may include a dynamic RAM (DRAM), a double date ratesynchronous dynamic RAM (DDR SDRAM), a static RAM (SRAM), a thyristorRAM (T-RAM), a zero-capacitor RAM (Z-RAM), etc. Exemplary ROM mayinclude a mask ROM (MROM), a programmable ROM (PROM), an erasableprogrammable ROM (EPROM), an electrically erasable programmable ROM(EEPROM), a compact disk ROM (CD-ROM), a digital versatile disk ROM,etc. In some embodiments, the storage device 150 may be implemented on acloud platform as described elsewhere in the disclosure.

In some embodiments, the storage device 150 may be connected to thenetwork 140 to communicate with one or more other components in theimaging system 100 (e.g., the processing engine 130, or the terminaldevice 160). One or more components in the imaging system 100 may accessthe data or instructions stored in the storage device 150 via thenetwork 140. In some embodiments, the storage device 150 may be part ofthe processing engine 130.

The terminal device 160 may be connected to and/or communicate with thePET scanner 110, the examining table 120, the processing engine 130,and/or the storage device 150. For example, the processing engine 130may acquire a scanning protocol from the terminal device 160. As anotherexample, the terminal device 160 may obtain image data from the PETscanner 110 and/or the storage device 150. In some embodiments, theterminal device 160 may include a mobile device 161, a tablet computer162, a laptop computer 163, or the like, or any combination thereof. Insome embodiments, the mobile device 161 may include a mobile phone, apersonal digital assistance (PDA), a gaming device, a navigation device,a point of sale (POS) device, a laptop, a tablet computer, a desktop, orthe like, or any combination thereof. In some embodiments, the terminaldevice 160 may include an input device, an output device, etc. The inputdevice may include alphanumeric and other keys that may be input via akeyboard, a touch screen (for example, with haptics or tactilefeedback), a speech input, an eye tracking input, a brain monitoringsystem, or any other comparable input mechanism. The input informationreceived through the input device may be transmitted to the processingengine 130 via, for example, a bus, for further processing. Other typesof the input device may include a cursor control device, such as amouse, a trackball, or cursor direction keys, etc. The output device mayinclude a display, a speaker, a printer, or the like, or any combinationthereof. In some embodiments, the external device 140 may be part of theprocessing engine 130.

This description is intended to be illustrative, and not to limit thescope of the present disclosure. Many alternatives, modifications, andvariations will be apparent to those skilled in the art. The features,structures, methods, and characteristics of the exemplary embodimentsdescribed herein may be combined in various ways to obtain additionaland/or alternative exemplary embodiments. For example, the storagedevice 150 may be a data storage including cloud computing platforms,such as, public cloud, private cloud, community, hybrid clouds, etc. Insome embodiments, the processing engine 130 may be integrated into thePET scanner 110. However, those variations and modifications do notdepart the scope of the present disclosure.

FIG. 2 is a block diagram illustrating an exemplary PET scanner 110according to some embodiments of the present disclosure. The PET scanner110 may include a detector 111 for detecting PET signals associated withlines of response 212.

As shown in FIG. 2, the detector 111 may include a plurality of detectormodules 211. The plurality of detector modules 211 may be arranged inthe form of a ring, a cylinder, a portion thereof, to surround thesubject being scanned. In some embodiments, the detector 111 may includea plurality of detector rings. In some embodiments, the plurality ofdetector modules 211 may be placed within the wall of the PET scanner110. In some embodiments, a plurality of detector module 211 may detectgamma rays. A patient injected with radiopharmaceuticals may lie on abed (e.g., the examining table 120) parallel to the z axis of the PETscanner 110. The radiopharmaceuticals may include radioisotopes thatdecay and emit gamma rays of characteristic energy. The gamma rayphotons may be generated in an electron-positron annihilation event andpropagate in opposite directions. For example, two gamma ray photons maytravel in opposite directions and detected by a couple of oppositedetector modules 211.

When the annihilation events occur within the PET scanner 110, they maybe detected as a coincidence event if both gamma ray photons strikedetector modules 211 substantially simultaneously. In order to validatea coincidence event, the processing engine 130 may detect the timeinformation of electrical pulses from the detector 111 when incidentgamma ray photons are detected.

As used herein, a line of response (LOR) may be determined by connectingthe couple of detector modules 211 of a coincidence event and theannihilation point may be determined based on the time information ofthe two single events. It should also be noted here that the “line ofresponse” or “LOR” used herein may be representative of a radiation ray,and not intended to limit the scope of the present disclosure. Theradiation ray used herein may include a particle ray, a photon ray, etc.The particle ray may include particles such as, a neutron, a proton, anelectron, a μ-meson, a heavy ion, or the like, or any combinationthereof. For example, the radiation ray may represent the intensity ofan X-ray beam passing through the subject in the case of a CT system. Asanother example, the radiation ray may represent the probability of apositron generated in the case of a PET system.

FIG. 3 is a block diagram illustrating an exemplary PET scanner 110according to some embodiments of the present disclosure. As shown inFIG. 3, the PET scanner 110 may include a PET detector module 310, aninstalling module 320, a fixing module 330, a position-limiting module340, and a subsidiary connection module 350.

The PET detector module 310 may be configured to detect gamma rays. ThePET detector module 310 may be the detector module 211 in FIG. 2. Thedetector module and the PET detector module may be used interchangeablyin the present disclosure.

The installing module 320 may be configured to install the PET detectormodule 310. In some embodiments, the PET detector module 310 may beinstalled at a part of the installing module 320 (e.g., a surface of theinstalling module 320). The PET detector module 310 may be installed atthe part of the installing module 320 through different installationmanners including, for example, gluing, welding, riveting, pressing,casting, pinning, buttoning, tying, sticking, clasping, plugging, screwconnection, or the like, or any combination thereof. For example, thePET detector module 310 may be connected with the installing module 320by a screw. In some embodiments, the installing module 320 may includeone or more small parts (e.g., a connection plate, or an axle hole). Theone or more small parts may facilitate connections between two or moreinstalling modules 320. For example, a plurality of installing modules320 that install a plurality of PET detector modules 310 thereon may beconnected with each other and form a detector ring. In some embodiments,the installing module 320 may include a chain piece. Detaileddescription of the chain piece may be found elsewhere in the presentdisclosure (e.g., in the description of FIG. 4, FIG. 8, FIG. 9, or FIG.11).

In some embodiments, the PET scanner 110 may include a detector. Thedetector may include a plurality of PET detector modules 310 and aplurality of installing modules 320 configured to install the pluralityof PET detector modules 310. The plurality of installing modules 320 maybe sequentially connected to form a ring structure. The plurality ofinstalling modules 320 may be connected together through differentconnection manners including, for example, gluing, welding, riveting,pressing, casting, pinning, buttoning, tying, sticking, clasping,plugging, screw connection, or the like, or any combination thereof. Thering structure may be a detachable and modular ring structure. The ringstructure may include an outer circumference surface and innercircumference surface spaced apart along the radial direction of thering structure. The plurality of PET detector modules 310 may becontinuously arranged along the inner circumference surface of the ringstructure. For example, the plurality of PET detector modules 310 may befixed with the ring structure by one or more screws.

The fixing module 330 may be configured to fix the PET detector module310 and/or the installing module 320. For example, a plurality of PETdetector modules 310 and a plurality of installing modules 320 may forma detector. The fixing module 330 may include a detector stabilizingcylinder configured to fix the detector. The detector may be fixed withthe detector stabilizing cylinder through different connection mannersincluding, for example, gluing, welding, riveting, pressing, casting,pinning, buttoning, tying, sticking, clasping, plugging, screwconnection, or the like, or any combination thereof. The fixing module330 may also include a fixing support configured to limit the detectorstabilizing cylinder. In some embodiments, the detector stabilizingcylinder may be rotatably limited on the fixing support. The movementsof the detector stabilizing cylinder along the axial direction and theradial direction may be limited. In some embodiments, the fixing supportmay limit the movements of the detector stabilizing cylinder by one ormore limiting parts (e.g., the position-limiting module 340). The fixingsupport may include one or more supporting feet and supporting rings. Insome embodiments, the fixing support may include two separate fixingsupports (e.g., a front fixing support and a rear fixing support).Detailed description of the detector stabilizing cylinder and the fixingsupport may be found elsewhere in the present disclosure (e.g., in thedescription of FIG. 14, FIG. 15, or FIG. 16).

The position-limiting module 340 may be configured to facilitate thelimiting operations of the fixing module 330. For example, the fixingsupport may limit the detector stabilizing cylinder through theposition-limiting module 340. In some embodiments, the position-limitingmodule 340 may include a rolling wheel, a gear wheel, or the like, orany combination thereof. The rolling wheel may include an axialposition-limiting wheel configured to limit the axial position of thedetector stabilizing cylinder and a radial position-limiting wheelconfigured to limit the radial position of the detector stabilizingcylinder. The rolling wheel may be fixed between a front fixing supportand a rear fixing support by a scrollable axis. In some embodiments, therolling wheel may be a drive wheel that drives the detector stabilizingcylinder to rotate on the fixing support. In some embodiments, one ormore rolling wheels may be distributed along the circumferentialdirection of the detector stabilizing cylinder. The number anddistribution pattern of the rolling wheels may not be limiting. Detaileddescription of the rolling wheel may be found elsewhere in the presentdisclosure (e.g., in the description of FIG. 15, FIG. 16, or FIG. 17).

The subsidiary connection module 350 may be configured to facilitateoperations of the PET detector module 310, the installing module 320,the fixing module 330, and/or the position-limiting module 340. Thesubsidiary connection module 350 may include a rotation axis, a brakepart, a connection part, a scrollable axis, or the like, or anycombination thereof. In some embodiments, the rotation axis may be usedto connect a plurality of chain pieces. In some embodiments, the brakepart may be used to immobilize the detector stabilizing cylinder. Insome embodiments, the connection part may be used to connect twoneighboring chain pieces. In some embodiments, the scrollable axis maybe used to fix a rolling wheel between the front fixing support and therear fixing support.

This description above is merely intended to be illustrative, and not tolimit the scope of the present disclosure. Many alternatives,modifications, and variations will be apparent to those skilled in theart. The features, structures, methods, and characteristics of theexemplary embodiments described herein may be combined in various waysto obtain additional and/or alternative exemplary embodiments. Forexample, the PET scanner 110 may include a shielding enclosuresurrounding the detector for shielding radiations. However, thosevariations and modifications do not depart the scope of the presentdisclosure.

FIG. 4 is schematic diagram illustrating an exemplary PET detectormodule 310 according to some embodiments of the present disclosure. ThePET detector module 310 may include a scintillator 410, a light guide420, and a photodetector 430. The light guide 420 may be opticallycoupled to the scintillator 410 to provide a light path to thephotodetector 430. In some embodiments, the photodetector 430 may be aphotomultiplier (PMT).

In some embodiments, the scintillator 410 may include an array ofscintillation crystals, and the detector module 310 may include morethan one photodetector. Incident gamma rays may strike the scintillator410 to produce small bursts of visible or invisible light. The visibleor invisible light may be converted to one or more electric signals(e.g., one or more electric pulses) by, for example, a photocathode ofthe PMT. In some embodiments, the electric pulses may be generated byamplifying electrons excited by the visible or invisible light through adynode string in the PMT.

The scintillator 410 may include different kinds of compounds. Exemplarycompounds may include Bismuth germinate (BGO), barium fluoride (BaFl),gadolinium silicate (GSO), Lutetium orthosilicate (LSO), LutetiumYttrium orthosilicate (LYSO), or the like, or any combination thereof.

It should be noted that the photodetector 430 may be but not limited tothe PMT. In some embodiments, the photodetector 430 may be a siliconphotomultiplier (SiPM), an avalanche photodiode (APD), or the like, orany combination thereof. Actually, any kind of sensor functioning asphotovoltaic conversion may be suitable in the present disclosure.

FIG. 5 illustrates an exemplary PET detector assembly 500 according tosome embodiments of the present disclosure. The PET detector assembly500 may include a PET detector module 510 and a chain piece 520. The PETdetector module 510 may detect incident gamma rays and generate one ormore electrical signals (e.g., one or more electric pulses). Theprocessing engine 130 may receive the electrical signals and determine aPET image based on the electrical signal. The PET detector module 510may be the PET detector module 310 in FIG. 3. The surface of the PETdetector module 510 away from the chain piece 520 may be flat or curved.The chain piece 520 may be configured to install the PET detector module510. The PET detector module 510 may be installed on one side of thechain piece 520 through different connection manners including, forexample, gluing, welding, riveting, pressing, casting, pinning,buttoning, tying, sticking, clasping, plugging, screw connection, or thelike, or any combination thereof.

As shown in FIG. 5, the chain piece 520 may include a convex part 521, arecessed part 522, an axle hole 523 inside the convex part 521, and anaxle hole 524 inside the recessed part 522. The convex part 521 may beformed on one end face of the chain piece 520, and the recessed part 522may be formed on the other end face of the chain piece 520. In someembodiments, the positions of the convex part 521 and the recessed part522 may be exchanged.

FIG. 6 illustrates an exemplary connection manner of a plurality of PETdetector assemblies 500 according to some embodiments of the presentdisclosure. A plurality of PET detector assemblies 500 may be connectedtogether end-to-end. The plurality of PET detector assemblies 500 may bearranged in the form of a ring, a cylinder, a portion thereof, etc. Thenumber of the plurality of detector assemblies 500 may be N. Where N maybe any integer, for example, 5, 10, 20, 40, etc. As shown in FIG. 6, twoneighboring PET detector assemblies 500 may be hinged together through aconvex part (e.g., a convex part 521 d) and a recessed part (e.g., arecessed part 522 a). Merely by way of example, if a chain piece 520 ais the first chain piece and a chain piece 520 d is the second chainpiece (e.g., the Nth chain piece), the convex part 521 d of the chainpiece 520 d may be coupled to the recessed part 522 a of the chain piece520 a. The chain piece 520 d and the chain piece 520 a may be hingedtogether by a rotation axis (not shown in FIG. 6) which is through theaxle hole 523 (as shown in FIG. 5) of the convex part 521 d and the axlehole 524 (as shown in FIG. 5) of the recessed part 522 a. Connectionmanners between a chain piece 520 b and a chain piece 520 c may besimilar to that of the chain piece 520 a and the chain piece 520 d, andis not repeated here.

FIG. 7 illustrates an exemplary detector ring 700 according to someembodiments of the present disclosure. As shown in FIG. 7, the detectorring 700 may include a plurality of PET detector assemblies 500. Chainpieces of the plurality of PET detector assemblies 500 may be hingedtogether end-to-end to connect the plurality of PET detector assemblies500 to form the detector ring 700. A direction a-a′ may represent theaxial direction of the detector ring 700, and a direction b-b′ mayrepresent the circumferential direction of the detector ring 700. Theplurality of PET detector assemblies 500 may be arranged along thedirection b-b′. The convex part 521 and the recessed part 522 of the PETdetector assembly 500 may be configured on both ends of the PET detectorassembly 500 along the direction b-b′.

FIG. 8 illustrates an exemplary PET detector assembly 800 according tosome embodiments of the present disclosure. The PET detector assembly800 may include a PET detector module 510 and a chain piece 520. The PETdetector module 510 may detect incident gamma rays and generate one ormore electrical signals (e.g., one or more electric pulses). Theprocessing engine 130 may receive the electrical signals and determine aPET image based on the electrical signals. The PET detector module 510may be the PET detector module 310 in FIG. 3. The surface of the PETdetector module 510 away from the chain piece 520 may be flat or curved.The chain piece 520 may be configured to install the PET detector module510. As shown in FIG. 8, the PET detector module 510 may include asliding part 511. The chain piece 520 may include a convex part 521, arecessed part 522, an axle hole 523 in the convex part 521, an axle hole524 in the recessed part 522, an installing groove 525, and aposition-limiting surface 526. When connecting the PET detector module510 with the chain piece 520, the sliding part 511 may be pushed intothe installing groove 525. In some embodiments, the position of theinstalling groove 525 and the sliding part 511 may be interchanged. Forexample, the installing groove 525 may be configured on the PET detectormodule 510 and the sliding part 511 may be configured on the chain piece520. The orientation of the installing groove 525 may be various. Anyorientation that enables the sliding connection between the PET detectormodule 510 and the chain piece 520 may be suitable. In some embodiments,the shapes of the installing groove 525 and the sliding part 511 may becompletely matched or fitted. The PET detector module 510 and the chainpiece 520 may be further fixed through a screw connection, gluing, etc.The position-limiting surface 526 may be located on one end face of thechain piece 520, for example, on the end face away from the convex part521. The position-limiting surface 526 may be an inclined surface.Functions of the position-limiting surface 526 will be discussed indetail in connection with FIG. 9.

FIG. 9 illustrates an exemplary connection manner of two PET detectorassemblies 800 according to some embodiments of the present disclosure.A PET detector assembly 800 a and a detector assembly 800 b may behinged together end-to-end. The detector assembly 800 a may include aPET detector module 510 a and a first chain piece 520 a. The detectorassembly 800 b may include a PET detector module 510 b and a secondchain piece 520 b. The hinged detector assembly 800 a and the detectorassembly 800 b may rotate around a rotation axle (not shown in FIG. 9)through an axle hole 524 b and form an angle. A position-limitingsurface 526 b may be located on one end face of the second chain piece520 b away from the convex part 521 b. The position-limiting surface 526b may be configured to push against an adjacent face of the first chainpiece 520 a during the rotation. The angle between the first chain piece520 a and the second chain piece 520 b may be limited by theposition-limiting surface 526 b. The angle may be limited to avoid acollision between the PET detector module 510 a and the PET detectormodule 510 b during the rotation.

FIG. 10 illustrates an exemplary detector ring 1000 according to someembodiments of the present disclosure. In some embodiments, the detectorring 1000 may include a detector ring 700 a, a detector ring 700 b, anda detector ring 700 c. The detector ring 700 a, the detector ring 700 b,and the detector ring 700 c may be arranged along the axial directiona-a′ of the detector ring 1000. The detector ring 700 a, the detectorring 700 b, and the detector ring 700 c may be connected by a pluralityof rotation axes. For example, a chain piece 520 a, a chain piece 520 b,and a chain piece 520 c along a same axial direction may be connected bya rotation axis 1010.

It should be noted that the detector ring 1000 may be not limited to thedetector rings 700 a, 700 b, and 700 c. In some embodiments, thedetector ring 1000 may include at least two detector rings 700. In someembodiments, to improve the imaging efficiency of the imaging system100, the length of the detector ring 1000 along a-a′ direction may belarge, for example, two meters. More detector rings 700 may beconnected, with increase of the length of the detector ring 1000 alonga-a′ direction.

FIG. 11 illustrates an exemplary PET detector assembly 1100 according tosome embodiments of the present disclosure. The PET detector assembly1100 may include a PET detector module 1110 and a chain piece 1120. ThePET detector module 510 may detect incident gamma rays and generate oneor more electrical signals (e.g., one or more electric pulses). Theprocessing engine 130 may receive the electrical signals and determine aPET image based on the electrical signals. The PET detector module 1110may be the PET detector module 310 in FIG. 3. The surface of the PETdetector module 1110 away from the chain piece 1120 may be flat orcurved. The chain piece 1120 may be configured to install the PETdetector module 1110. The PET detector module 1110 may be installed onone side of the chain piece 1120 through different connection mannersincluding, for example, gluing, welding, riveting, pressing, casting,pinning, buttoning, tying, sticking, clasping, plugging, screwconnection, or the like, or any combination thereof.

As shown in FIG. 11, the chain piece 1120 may include first hinge parts1121 a and 1121 b (e.g., first hinge part 1121 as shown in FIG. 12),second hinge parts 1122 a and 1122 b (e.g., second hinge part 1122 asshown in FIG. 12), a stabilizing plate 1123, and fixing holes 1124 a and1124 b formed on the stabilizing plate 1123. The length of the firsthinge part 1121 a (or the first hinge part 1121 b) may be different orsame with the length of the second hinge part 1122 a (or the secondhinge part 1122 b).

FIG. 12 illustrates an exemplary detector ring 1200 according to someembodiments of the present disclosure. As shown in FIG. 11 and FIG. 12,the first hinge part 1121 and the second hinge part 1122 may be arrangedalong the circumferential direction b-b′ of the detector ring 1200. Thefirst hinge part 1121 a and the first hinge part 1121 b may berespectively configured at two end faces of the chain piece 1120 alongthe axial direction a-a′ of the detector ring 1200. The second hingepart 1122 a and the second hinge art 1122 b may also be respectivelyconfigured at two end faces of the chain piece 1120 along the axialdirection a-a′ of the detector ring 1200. In some embodiments, thedistance from the first hinge part 1121 a to the first hinge part 1121 balong the axial direction a-a′ of the detector ring 1200 may be greaterthan the distance from the second hinge part 1122 a to the second hingepart 1122 b along the axial direction a-a′ of the detector ring 1200.Two neighboring chain pieces 1120 (e.g. a first chain piece, and asecond chain piece) of the detector ring 1200 may be connected bycoupling the first hinge parts 1121 of one chain piece 1120 (e.g., thefirst chain piece) with the second hinge parts 1122 of the other chainpiece 1120 (e.g., the second chain piece) by a rotation axis (not shownin FIG. 12). The rotation axis may be located at a position of the firsthinge part 1121 and/or the second hinge part 1122 close to the center ofthe detector ring 1200. Along the axial direction a-a′ of the detectorring 1200, the first hinge parts 1121 may be located outside of thesecond hinge parts 1122. In some embodiments, a connection part 1210 maybe further adopted to connect the two neighboring chain pieces 1120. Theconnection part 1210 may connect the two stabilizing plates 1123 of thetwo neighboring chain pieces 1120 via the two fixing holes 1124. Theshape of the stabilizing plate 1123 may be various, such as rectangular,trapezoid, triangle, circle, irregular shape, etc. Any shape capable ofconnecting the two neighboring chain pieces 1120 may be suitable in thepresent disclosure.

In some embodiments, the stabilizing plate 1123 may be optional. Forexample, the connection part 1210 may be directly connected with thechain piece 1120 on the side of the chain piece 1120 away from the PETdetector module 1110. The connection part 1210 may be fixed with thechain piece 1120 through different connection manners including, forexample, gluing, welding, riveting, pressing, casting, pinning,buttoning, tying, sticking, clasping, plugging, screw connection, or thelike, or any combination thereof. Through the connection of the firsthinge parts 1121, the second hinge parts 1122, and the connection part1210, an adjacent angle between the two neighboring chain pieces 1120 ofthe detector ring 1200 along the circumferential direction b-b′ of thedetector ring 1200 may be determined. With a total arc angle of 360°,the number of chain pieces 1120 along the circumferential direction b-b′of the detector ring 1200 may be determined based on the adjacent angle.The adjacent angle may be adjusted based on different length of theconnection part 1210. And then the number of chain pieces 1120 along thecircumferential direction b-b′ of the detector ring 1200 may beadjusted. For example, as shown in FIG. 12, sixteen chain pieces 1120may be arranged along the circumferential direction b-b′ of the detectorring 1200. In some embodiments, the number of the PET detector modules1110 and the number of the chain pieces 1120 may not be one-to-one. Forexample, one PET detector module 1110 may be installed on more than onechain pieces 1120, or more than one PET detector modules 1110 may beinstalled on one chain piece 1120.

FIG. 13 illustrates an exemplary detector ring 1300 according to someembodiments of the present disclosure. The detector ring 1300 mayinclude a connection part 1310. The length of the connection part 1310may be lower than the length of the connection part 1210 shown in FIG.12. The number of chain pieces 1120 around the detector ring 1300 maybe, for example, twenty-four. The structure and connection manners ofthe detector ring 1300 may be similar to that of the detector ring 1200,and is not repeated here.

It should be noted that the description of the PET detector assembly1100, the detector 1200, and the detector ring 1300 is intended to beillustrative, and not limit the scope of the present disclosure. Manyalternatives, modifications, and variations will be apparent to thoseskilled in the art. The features, structures, methods, andcharacteristics of the exemplary embodiments described herein may becombined in various ways to obtain additional and/or alternativeexemplary embodiments. For example, the detector ring 1200 and/or thedetector ring 1300 may include more than one detector rings along theaxial direction a-a′ of the detector ring. Lengths of a plurality ofconnection parts 1210 arranged along the circumferential direction ofthe detector ring 1200 may be same or different. Similarly, lengths of aplurality of connection parts 1310 arranged along the circumferentialdirection of the detector ring 1300 may be same or different. As anotherexample, lengths of a plurality of chain pieces 1120 of the detectorring 1200 and/or the detector ring 1300 along the axial direction a-a′of the detector ring may be same or different.

FIG. 14 illustrates an exemplary PET detector 1400 according to someembodiments of the present disclosure. The PET detector 1400 may includeone or more detector modules 1410, a detector stabilizing cylinder 1420,and fixing supports 1430 a and 1430 b. Structures and/or components ofthe one or more detector modules 1410 may be found in FIG. 4 and itsdescription. In some embodiments, the one or more detector modules 1410may also be a plurality of PET detector assemblies (e.g., the PETdetector assembly 500, the PET detector assembly 800, or the PETdetector assembly 1100). In some embodiments, the one or more detectormodules 1410 may be configured to form a detector ring (e.g., thedetector ring 700, the detector ring 1000, the detector ring 1200, orthe detector ring 1300). The one or more detector modules 1410 may befixed with the detector stabilizing cylinder 1420 through differentconnection manners including, for example, gluing, welding, riveting,pressing, casting, pinning, buttoning, tying, sticking, clasping,plugging, screw connection, or the like, or any combination thereof. Thedetector stabilizing cylinder 1420 may be limited by the fixing supports1430 a and 1430 b. In some embodiments, the fixing support 1430 a may bealso referred to as a front fixing support, and the fixing support 1430b may be also referred to as a rear fixing support. The fixing support1430 a may include a supporting foot 1431 a and a supporting ring 1432a. The fixing support 1430 b may include a supporting foot 1431 b and asupporting ring 1432 b. The detector stabilizing cylinder 1420 may beinstalled between the fixing support 1430 a and the fixing support 1430b. Merely by way of example, the detector stabilizing cylinder 1420 maybe installed between the supporting ring 1432 a and the supporting ring1432 b. The detector stabilizing cylinder 1420 may be rotatably limitedon the fixing support 1430 a and the fixing support 1430 b. The detectorstabilizing cylinder 1420 may rotate along the circumferential directionof the detector stabilizing cylinder 1420. Inner diameters of thesupporting ring 1432 a and the supporting ring 1432 b may be lower thanthe external diameter of the detector stabilizing cylinder 1420, and thedetector stabilizing cylinder 1420 may be limited in the axial direction(the X-axis direction). Lubricants may be applied on contact surfacesbetween the detector stabilizing cylinder 1420 and the supporting rings1432 a and 1432 b. The lubricants may reduce the resistance between thedetector stabilizing cylinder 1420 and the supporting rings 1432 a and1432 b when the detector stabilizing cylinder 1420 is rotating.

FIG. 15 illustrates an exemplary detector stabilizing cylinder 1420according to some embodiments of the present disclosure. The detectorstabilizing cylinder 1420 may include a plurality of detector fixingholes 1501. The one or more detector modules 1410 may be fixed on theinner wall of the detector stabilizing cylinder 1420 through theplurality of detector fixing holes 1501. The detector stabilizingcylinder 1420 may also include a radial position-limiting surface 1502,axial position-limiting surfaces 1503 a and 1503 b, flanging structures1504 a and 1504 b. In some embodiments, the detector stabilizingcylinder 1420 may not include the plurality of fixing holes 1501, andthe one or more detector modules 1410 may be fixed with the inner wallof the detector stabilizing cylinder 1420 through other various manners,for example, gluing, pressing, etc.

In some embodiments, a drive part may be installed in contact with theradial position-limiting surface 1502 and/or the axial position-limitingsurface 1503. The drive part may be configured to enable the detectorstabilizing cylinder 1420 to rotate along the circumferential directionof the supporting ring 1432 a and the supporting ring 1432 b (as shownin FIG. 14). The drive part may directly or indirectly drive thedetector stabilizing cylinder 1420 to rotate or drive the detectorstabilizing cylinder 1420 to rotate under an external force (e.g., adrive motor). In some embodiments, the drive part may be a rolling wheel(as will be described in detail in connection with FIG. 16).

This description is intended to be illustrative, and not to limit thescope of the present disclosure. Many alternatives, modifications, andvariations will be apparent to those skilled in the art. The features,structures, methods, and characteristics of the exemplary embodimentsdescribed herein may be combined in various ways to obtain additionaland/or alternative exemplary embodiments.

FIG. 16 illustrates the front view of an exemplary detector stabilizingcylinder 1420 according to some embodiments of the present disclosure.Rolling wheels 1601 a and 1601 b may be installed in contact with theradial position-limiting surface 1502 (as shown in FIG. 15) of thedetector stabilizing cylinder 1420. The rolling wheels 1601 a and 1601 bmay be configured to limit the detector stabilizing cylinder 1420 in theradial direction (the Y-axis direction as shown in FIG. 15). The rollingwheels 1601 a and 1601 b may be referred to as radial position-limitingwheels 1601 a and 1601 b. A radial position-limiting wheel 1601 maylimit the movement of the detector stabilizing cylinder 1420 in theradial direction (the Y-axis direction as shown in FIG. 15). The radialposition-limiting wheels 1601 a and 1601 b may be located beneath thehorizontal center line (marked as “a” in FIG. 16) of the detectorstabilizing cylinder 1420. The radial position-limiting wheels 1601 aand 1601 b may be respectively located at both sides of the verticalcenter line (marked as “b” in FIG. 16) of the detector stabilizingcylinder 1420. At least two radial position-limiting wheels 1601 may beinstalled to limit the movement of the detector stabilizing cylinder1420 in the radial direction (the Y-axis direction as shown in FIG. 15).The more the number of the radial position-limiting wheel 1601, thebetter stability of the detector stabilizing cylinder 1420.

In some embodiments, one of the radial position-limiting wheels 1601 aand 1601 b (e.g., the radial position-limiting wheels 1601 a) may be adrive wheel that is connected with an external force (e.g., a drivemotor (not shown in FIG. 16)). The drive wheel may drive the detectorstabilizing cylinder 1420 to rotate along the circumferential directionunder the power of the external force. In some embodiments, the radialposition-limiting wheel 1601 a and/or the radial position-limiting wheel1601 b itself may be a motive wheel that provides power for the rotationof the detector stabilizing cylinder 1420.

FIG. 17 illustrates an exemplary PET detector 1700 according to someembodiments of the present disclosure. The PET detector 1700 may includea plurality of axial position-limiting wheels (e.g., an axialposition-limiting wheel 1710 a, or an axial position-limiting wheel 1710b). The axial position-limiting wheel 1710 a (or the axialposition-limiting wheel 1710 b) may be a rolling wheel configured tolimit the movement of the detector stabilizing cylinder 1420 in theaxial direction (shown as the X-axis direction in FIG. 17). The detectorstabilizing cylinder 1420 may include axial position-limiting surfaces1503 a and 1503 b (as shown in FIG. 15). The axial position-limitingwheel 1710 a (or the axial position-limiting wheel 1710 b) may beinstalled in contact with the axial position-limiting surfaces 1503 aand 1503 b of the detector stabilizing cylinder 1420. The detectorstabilizing cylinder 1420 may rotate along the circumferential directionof the detector stabilizing cylinder 1420 under the limit of theplurality of axial position-limiting wheels and radial position-limitingwheels (e.g., a radial position-limiting wheel 1601 a, or a radialposition-limiting wheel 1601 b).

In some embodiments, the axial position-limiting wheel 1710 a and/or theaxial position-limiting wheel 1710 b may include a number of sub-rollingwheels. The sub-rolling wheels will be discussed in detail in connectionwith FIG. 19. In some embodiments, the PET detector 1700 may include atleast three axial position-limiting wheels 1710 a (or axialposition-limiting wheels 1710 b) and at least three radialposition-limiting wheels 1601 a (or radial position-limiting wheels 1601b). The at least three axial position-limiting wheels 1710 a (or axialposition-limiting wheels 1710 b) and at least three radialposition-limiting wheels 1601 a (or radial position-limiting wheels 1601b) may be uniformly distributed along the circumferential direction ofthe detector stabilizing cylinder 1420. In some embodiments, the PETdetector 1700 may include at least one axial position-limiting wheel1701 a (or axial position-limiting wheel 1701 b) and at least two radialposition-limiting wheels 1601 a (or radial position-limiting wheels 1601b). The at least one axial position-limiting wheel 1701 a (or axialposition-limiting wheel 1701 b) and at least two radialposition-limiting wheels 1601 a (or radial position-limiting wheels 1601b) may be uniformly distributed along the circumferential direction ofthe detector stabilizing cylinder 1420. The structure of the PETdetector 1700 may be similar to that of the PET detector 1400, and isnot repeated here.

FIG. 18 illustrates the front view of an exemplary PET detector 1700according to some embodiments of the present disclosure. As shown inFIG. 18, the PET detector 1700 may include four axial position-limitingwheels 1710 a, 1710 b, 1710 c, and 1710 d. The PET detector 1700 mayalso include four radial position-limiting wheels 1601 a, 1601 b, 1601c, and 1601 d. The four axial position-limiting wheels and the fourradial position-limiting wheels may be uniformly distributed along thecircumferential direction of the detector stabilizing cylinder 1420. Theaxial position-limiting wheel 1710 and the radial position-limitingwheel 1601 may be alternately distributed along the circumferentialdirection of the detector stabilizing cylinder 1420.

In some embodiments, the movement of the detector stabilizing cylinder1420 may be limited in the axial direction and the radial directionthrough one rolling wheel. The rolling wheels may not differentiate anaxial position-limiting wheel or a radial position-limiting wheel. Insome embodiments, the PET detector 1700 may include more than four axialposition-limiting wheels and four radial position-limiting wheels. Themore the number of the axial position-limiting wheel and the radialposition-limiting wheel, the better rigidity of the PET detector 1700.

This description is intended to be illustrative, and not to limit thescope of the present disclosure. Many alternatives, modifications, andvariations will be apparent to those skilled in the art. The features,structures, methods, and characteristics of the exemplary embodimentsdescribed herein may be combined in various ways to obtain additionaland/or alternative exemplary embodiments.

FIG. 19 illustrates the side view of an exemplary PET detector 1700according to some embodiments of the present disclosure. As shown inFIG. 19, an axial position-limiting wheel 1710, a radialposition-limiting wheel 1601 a, and/or a radial position-limiting wheel1601 b may be fixed between a supporting ring 1432 a and a supportingring 1432 b through a scrollable axis (e.g., a scrollable axis 1910 a, ascrollable axis 1910 b, or a scrollable axis 1910 c). The axialposition-limiting wheel 1710 may include four sub-rolling wheels 1711 a,1711 b, 1711 c, and 1711 d. The four sub-rolling wheels 1711 a, 1711 b,1711 c, and 1711 d may be installed in contact with the axialposition-limiting surfaces 1503 a and 1503 b (as shown in FIG. 15) ofthe detector stabilizing cylinder 1420.

FIG. 20 illustrates an exemplary PET detector 1700 according to someembodiments of the present disclosure. The PET detector 1700 may includea brake part (not shown in FIG. 20). The brake part may be configured tobrake or immobilize the detector stabilizing cylinder. In someembodiments, the brake part may be a screw, a rivet, a block, etc. Forexample, the screw may run through an outside surface 1433 of thesupporting ring 1432 and an axial end face 1421 of the detectorstabilizing cylinder 1420. By fixing the screw, the detector stabilizingcylinder 1420 may be braked or immobilized and may not rotate.

Having thus described the basic concepts, it may be rather apparent tothose skilled in the art after reading this detailed disclosure that theforegoing detailed disclosure is intended to be presented by way ofexample only and is not limiting. Various alterations, improvements, andmodifications may occur and are intended to those skilled in the art,though not expressly stated herein. These alterations, improvements, andmodifications are intended to be suggested by the present disclosure,and are within the spirit and scope of the exemplary embodiments of thepresent disclosure.

Moreover, certain terminology has been used to describe embodiments ofthe present disclosure. For example, the terms “one embodiment,” “anembodiment,” and/or “some embodiments” mean that a particular feature,structure or characteristic described in connection with the embodimentis included in at least one embodiment of the present disclosure.Therefore, it is emphasized and should be appreciated that two or morereferences to “an embodiment” or “one embodiment” or “an alternativeembodiment” in various portions of this specification are notnecessarily all referring to the same embodiment. Furthermore, theparticular features, structures or characteristics may be combined assuitable in one or more embodiments of the present disclosure.

Further, it will be appreciated by one skilled in the art, aspects ofthe present disclosure may be illustrated and described herein in any ofa number of patentable classes or context including any new and usefulprocess, machine, manufacture, or composition of matter, or any new anduseful improvement thereof. Accordingly, aspects of the presentdisclosure may be implemented entirely hardware, entirely software(including firmware, resident software, micro-code, etc.) or combiningsoftware and hardware implementation that may all generally be referredto herein as a “unit,” “module,” or “system.” Furthermore, aspects ofthe present disclosure may take the form of a computer program productembodied in one or more computer readable media having computer readableprogram code embodied thereon.

We claim:
 1. A PET detector, comprising: a plurality of detectormodules; and a plurality of installing modules configured to install theplurality of detector modules, wherein the plurality of installingmodules are coupled together to form a detector ring.
 2. The PETdetector of claim 1, wherein at least one of the plurality of installingmodules includes a chain piece, and the chain piece further includes aninstalling groove on a surface connected to one of the plurality ofdetector modules, the one of plurality of detector modules furtherincludes a sliding part corresponding to the installing groove, andwherein the sliding part is installed in the installing groove.
 3. ThePET detector of claim 1, wherein the plurality of installing modulesinclude a first chain piece and a second chain piece, the first chainpiece and the second chain piece being adjacent, wherein each of thefirst chain piece and the second chain piece includes: a convex part atone end along a circumferential direction of the detector ring; and arecessed part at the other end along the circumferential direction ofthe detector ring, wherein the convex part of the first chain piece iscoupled to the recessed part of the second chain piece via a rotationaxis.
 4. The PET detector of claim 3, wherein the second chain piecefurther includes a position-limiting surface on one end of the secondchain piece adjacent to the first chain piece, and wherein theposition-limiting surface is configured to determine an angle formed bythe first chain piece and the second chain piece.
 5. The PET detector ofclaim 1, wherein the plurality of installing modules include a firstchain piece and a second chain piece, the first chain piece and thesecond chain piece being adjacent, wherein each of the first chain pieceand the second chain piece includes two hinge parts on both ends along acircumferential direction of the detector ring, and a rotation axiscorresponding to each of the two hinge parts, wherein the first chainpiece and the second chain piece are coupled together by the respectivehinge parts and the rotation axis.
 6. The PET detector of claim 5,wherein the rotation axis is located at a position of the hinge partclose to the center of the detector ring.
 7. The PET detector of claim6, further comprising: a connection part configured to connect the firstchain piece and the second chain piece.
 8. The PET detector of claim 7,wherein each of the first chain piece and the second chain piece furtherincludes a stabilizing plate and the connection part is configured toconnect the stabilizing plates of the first chain piece and the secondchain piece.
 9. The PET detector of claim 1, further comprising: atleast two detector rings formed by the plurality of detector modules andthe plurality of installing modules, wherein the at least two detectorrings are arranged parallel to an axial direction of the at least twodetector rings.
 10. A PET detector, comprising: a plurality of detectormodules; and a plurality of installing modules configured to install theplurality of detector modules, the plurality of installing modules beingsequentially connected to form a detachable ring structure, wherein thedetachable ring structure includes an outer circumference surface and aninner circumference surface spaced apart along a radial direction of thedetachable ring structure, and the plurality of detector modules arecontinuously arranged along the inner circumference surface of thedetachable ring structure.
 11. A PET frame, comprising: a detectorstabilizing cylinder configured to stabilize one or more detectormodules; and a fixing support configured to support the detectorstabilizing cylinder, wherein the detector stabilizing cylinder isrotatably fixed on the fixing support.
 12. The PET frame of claim 11,wherein the fixing support is configured to fix the detector stabilizingcylinder through a rolling wheel.
 13. The PET frame of claim 12, whereinthe fixing support includes a front fixing support and a rear fixingsupport, and the rolling wheel is fixed between the front fixing supportand the rear fixing support by a scrollable axis.
 14. The PET frame ofclaim 12, wherein the rolling wheel includes at least two rolling wheelsthat are located on both sides of a vertical center line of the detectorstabilizing cylinder, respectively, and are beneath a horizontal centerline of the detector stabilizing cylinder.
 15. The PET frame of claim12, wherein the rolling wheel includes at least one drive wheelconfigured to drive the detector stabilizing cylinder to rotate on thefixing support.
 16. The PET frame of claim 12, wherein the rolling wheelincludes: an axial position-limiting wheel configured to limit an axialposition of the detector stabilizing cylinder; and a radialposition-limiting wheel configured to limit a radial position of thedetector stabilizing cylinder.
 17. The PET frame of claim 12, whereinthe rolling wheel includes at least one axial position-limiting wheeland at least two radial position-limiting wheels.
 18. The PET frame ofclaim 17, wherein the at least one axial rolling wheel and the at leasttwo radial position-limiting wheels are uniformly distributed along acircumferential direction of the detector stabilizing cylinder.
 19. ThePET frame of claim 12, wherein the rolling wheel includes four axialposition-limiting wheels and four radial position-limiting wheels. 20.The PET frame of claim 11, further comprising a brake part configured toimmobilize the detector stabilizing cylinder.